Permeability separation devices (permeators) in which the membrane takes the form of selectively permeable, hairlike, hallow fiber lengths are now well known. The latter membrane form is particularly suited for the recovery of water from brines by reverse osmosis because the fibers do not require support against the large transmembrane pressure differentials which must be employed in this process. However, the economies of fabrication costs and space utilization that might be anticipated for large scale units of this type have not been realizeable because the cost for adequately pressure-resistant casings (and associated plumbing), of conventional design, goes up disproportionately as the size of the unit is increased. On the other hand, the use of a number of smaller scale units in parallel results in more cumbersome and expensive external plumbing and instrumentation. Economically priced water of adequate quality for domestic and industrial use is unavailable or is becoming increasingly less available in many parts of the world. It is thus highly desirable to be able to recover such water from the oceans, from brackish water bodies, etc., at the lowest possible cost per unit volume.
The primary object of the present invention is to provide a hollow fiber permeator unit which costs less, per unit volume of capacity, to make and to use.
An additional object is to provide a hollow fiber permeator that is simpler to fabricate, more reliable and easier to maintain than conventional permeability separatory devices.
A further object is to reduce the requirement for expensive materials and fabrication procedures in the manufacture of hollow fiber permeators.
Still another object is to provide a permeator design that is particularly suited for large scale units capable of processing hundreds of thousands of gallons of fluid per day.
It is also an object to provide a hollow fiber permeator which may be operated in a pressure balanced condition, i.e., with equal fluid pressures on the opposed faces of the tubesheet.
A particular object is to provide a design which avoids lateral interruptions in the casing integrity and utilizes the feed conduit/tubesheet assembly for additional casing stiffening and support, thereby making possible the use, in economical amounts, of lightweight, high stength non-metallic casing materials.
Another object is to provide a hollow fiber permeator in which the length of the flow path between the fibers is minimized and feed "polarization" tendencies are reduced.
An additional oject is to eliminate or drastically reduce the need for baffles, seals and internal hardware in hollow fiber permeator units.
It is also an object to provide a large-scale permeator design that can readily be adapted to small-scale devices and which is suitable for all manners of permeability separatory processes that may be carried out with hollow fibers.
Other objects will be made apparent to those skilled in the art by the following disclosure.